1. Field of the Invention
The present invention relates to universal joints, and more particularly, to such a joint used in combination with an impact wrench.
2. Prior Art
The use of universal joints in industry to tighten nuts by repeated blows automatically applied by compressed air and similar energy sources is well known in the art. One such example of use is in the automotive industry where nuts are applied and removed from tires. An air-driven impact wrench is usually coupled to a universal joint in order to remove the nuts or to tighten them quickly and easily. Other applications of this type include the tightening or removal of nuts and bolts from various other parts of the automobile. In such applications it is often very difficult for the user to obtain a proper grip of the bolt head with the universal joint. For example, many times the bolt to be removed is in a different axial alignment compared to the wrench and the universal joint. It thus becomes necessary for the user to remove other sections of the automobile such that proper axial alignment of the universal joint in the bolt to be removed can be obtained. If removal of a section is not possible, the user generally has to twist the universal joint so as to mate with the nut and then retwist the joint in order to remove it after the operation is completed. Such procedures have the obvious shortcoming in that they are time consuming.
In another application, where universal joints in impact wrenches have been extensively used, is in mass production, and more specifically, an assembly line system. In such a system, many times the part to be assembled comes on an automatic conveyor in front of the assembler. The assembler then inserts the bolt or nut and the like and attaches it by means of an impact wrench. Many times such bolts or nuts are inserted into the device such that the tool cannot be inserted in a straight line with respect to the nut or bolt. In such applications the user must twist or otherwise position the impact wrench so as to be in proper alignment with the nut to be removed or inserted. When the operation is completed, the joint must be retwisted so that it can be removed. While such twisting action may be achieved by various types of universal joints, there is still the problem of removal of the joint after each use. Today many assembly line operations are being automated and there is a need for the attaching head, or socket of the universal joint to be able to return to its original position after each use.
Other shortcomings of prior art universal joints are breakage due to the amount of axial forces applied to the device, and lack of "feel" when the device engages the nut or bolt.
One such prior art device which exemplifies these shortcomings is disclosed in McPeak, U.S. Pat. No. 3,855,884. McPeak teaches a conventional universal joint which is modified by an elongated output shaft having a sliding collar. The shaft carries a flange near its end to prevent removal of the collar. When the collar is slid from one position to another, the universal joint may be moved to various positions. It should be noted that such device has the obvious shortcoming in that it is only flexible at one end thereof. Thus, it can only be inserted or attached along the horizontal axis of the universal joint to the impact wrench. This prevents needed flexibility. Moreover, such device does not have an internal spring positioned between two ball joints to increase axial flexibility and retard breakage.
Another prior art impact wrench device is disclosed by Triplett et al., U.S. Pat. No. 3,779,105. Triplett discloses a fastener tool for use with special fasteners comprising a sleeve rigidly secured in a housing having a head engaging end extending from the housing, and a socket rotatably secured to the sleeve. A spring is also disposed in the housing in order to increase the flexibility of the device. However, such device suffers from the shortcoming in that each end thereof must be in the same alignment with the impact wrench for proper use. Thus, it cannot easily be attached to a bolt at various angles, and there is no external spring which may be modified and controlled.
The present invention provides a universal joint which is flexible at each end thereof and which has increased flexibility because of various internal and external springs disposed therein. By the use of the present invention, the socket head returns to its original position after each use. Moreover, the socket head and the attaching head may be rotatably positioned thus permitting the universal joint of the present invention to be used in a wide range of applications without requiring the impact wrench to occupy the same axial direction as the bolt to which the universal joint is attached.